1. Field of the Invention
The present invention relates generally to power generation controlling devices for vehicles, and, in particular to a power generation controlling device that controls power generation of a power generator mounted on a vehicle, such as a passenger car and a truck.
2. Description of the Related Art
In recent years, for controlling a vehicle system, reduced idling rotation and reduced friction have been made to improve vehicle fuel efficiency. On the other hand, because of increase in an electrical load caused by increasing power consumption in the vehicle system, torque fluctuation in an engine caused by operation of a power generator significantly affects behavior of the engine rotation. Therefore, through control that allows coordination between engine control and power generation control of the power generator, both stable power supply and stable idle rotation can be achieved. Control that achieves improvement in fuel efficiency by a deceleration regeneration effect can be performed. To actualize the above, a large amount of information is required to be exchanged between an engine controlling device and a power generation controlling device mounted on the power generator. For example, in Japanese Patent Laid-open Publication No. 2002-325085, digital communication, such as that using local interconnect network (hereinafter referred to as LIN) protocol, that requires little increase in communication lines and can be achieved at a low cost, is used.
The digital communication using LIN protocol, disclosed in Japanese Patent Laid-open Publication No. 2002-325085, can be achieved at a low cost. However, communication speed is slow. Therefore, when communication frames increases due to increasing information, communication (i.e., transmission and reception) are required to be performed divided over several transmitting and receiving operations. As a result, communication delay increases. Therefore, the method disclosed in Japanese Patent Laid-open Publication No. 2002-325085 is not suitable for communication of signals, such as power generation information and power generation amount information in which communication delay becomes a problem. An idea to solve this problem, a method in which frequency of communication frames requiring speed is increased can be considered. However, communication schedule becomes complicated so that designing overall software becomes difficult. Therefore, a method such as this is difficult to use.